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<title>Debugging with GDB: Line Tables In Python</title>

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<a name="Line-Tables-In-Python"></a>
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<p>
Next: <a href="Breakpoints-In-Python.html#Breakpoints-In-Python" accesskey="n" rel="next">Breakpoints In Python</a>, Previous: <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python" accesskey="p" rel="prev">Symbol Tables In Python</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="Manipulating-line-tables-using-Python"></a>
<h4 class="subsubsection">23.2.2.28 Manipulating line tables using Python</h4>

<a name="index-line-tables-in-python"></a>
<a name="index-gdb_002eLineTable"></a>

<p>Python code can request and inspect line table information from a
symbol table that is loaded in <small>GDB</small>.  A line table is a
mapping of source lines to their executable locations in memory.  To
acquire the line table information for a particular symbol table, use
the <code>linetable</code> function (see <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python">Symbol Tables In Python</a>).
</p>
<p>A <code>gdb.LineTable</code> is iterable.  The iterator returns
<code>LineTableEntry</code> objects that correspond to the source line and
address for each line table entry.  <code>LineTableEntry</code> objects have
the following attributes:
</p>
<dl>
<dt><a name="index-LineTableEntry_002eline"></a>Variable: <strong>LineTableEntry.line</strong></dt>
<dd><p>The source line number for this line table entry.  This number
corresponds to the actual line of source.  This attribute is not
writable.
</p></dd></dl>

<dl>
<dt><a name="index-LineTableEntry_002epc"></a>Variable: <strong>LineTableEntry.pc</strong></dt>
<dd><p>The address that is associated with the line table entry where the
executable code for that source line resides in memory.  This
attribute is not writable.
</p></dd></dl>

<p>As there can be multiple addresses for a single source line, you may
receive multiple <code>LineTableEntry</code> objects with matching
<code>line</code> attributes, but with different <code>pc</code> attributes.  The
iterator is sorted in ascending <code>pc</code> order.  Here is a small
example illustrating iterating over a line table.
</p>
<div class="smallexample">
<pre class="smallexample">symtab = gdb.selected_frame().find_sal().symtab
linetable = symtab.linetable()
for line in linetable:
   print &quot;Line: &quot;+str(line.line)+&quot; Address: &quot;+hex(line.pc)
</pre></div>

<p>This will have the following output:
</p>
<div class="smallexample">
<pre class="smallexample">Line: 33 Address: 0x4005c8L
Line: 37 Address: 0x4005caL
Line: 39 Address: 0x4005d2L
Line: 40 Address: 0x4005f8L
Line: 42 Address: 0x4005ffL
Line: 44 Address: 0x400608L
Line: 42 Address: 0x40060cL
Line: 45 Address: 0x400615L
</pre></div>

<p>In addition to being able to iterate over a <code>LineTable</code>, it also
has the following direct access methods:
</p>
<dl>
<dt><a name="index-LineTable_002eline"></a>Function: <strong>LineTable.line</strong> <em>(line)</em></dt>
<dd><p>Return a Python <code>Tuple</code> of <code>LineTableEntry</code> objects for any
entries in the line table for the given <var>line</var>, which specifies
the source code line.  If there are no entries for that source code
<var>line</var>, the Python <code>None</code> is returned.
</p></dd></dl>

<dl>
<dt><a name="index-LineTable_002ehas_005fline"></a>Function: <strong>LineTable.has_line</strong> <em>(line)</em></dt>
<dd><p>Return a Python <code>Boolean</code> indicating whether there is an entry in
the line table for this source line.  Return <code>True</code> if an entry
is found, or <code>False</code> if not.
</p></dd></dl>

<dl>
<dt><a name="index-LineTable_002esource_005flines"></a>Function: <strong>LineTable.source_lines</strong> <em>()</em></dt>
<dd><p>Return a Python <code>List</code> of the source line numbers in the symbol
table.  Only lines with executable code locations are returned.  The
contents of the <code>List</code> will just be the source line entries
represented as Python <code>Long</code> values.
</p></dd></dl>

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